Vehicle cooling and heating device

ABSTRACT

The invention concerns a device comprising, additionally to the main thermostat ( 6 ) for interrupting the circulation of the refrigerant in the cooling radiator ( 2 ) to accelerate the heat engine ( 1 ) heating for a cold start, a three-way valve ( 10 ) which, when the temperature rises above the threshold opening the main thermostat ( 6 ), enables to gradually reduce the fluid flow rate in the heating radiator ( 3 ) then to cancel it so as to increase the fluid flow rate in the cooling radiator and consequently enhance the engine cooling efficiency.

The invention relates to a device for cooling the heat engine andheating the passenger compartment of a motor vehicle, comprising a firstheat exchanger suitable for contributing to a transfer of heat from aheat transfer fluid to the atmosphere, a second heat exchanger suitablefor contributing to a transfer of heat from the heat transfer fluid tothe passenger compartment, a pump suitable for making the fluid flow inthe engine and in two branches in parallel respectively containing thefirst and second exchangers, and switching means, which enable the fluiddriven by the pump to flow or not to flow in each of said exchangers,the switching means comprising a first valve suitable for preventingflow of the fluid in the first exchanger when its temperature is lowerthan a first threshold and for allowing it when said temperature ishigher than the first threshold.

A temperature of the heat transfer fluid lower than the first threshold,which is 80° C. for example, means that the engine is itself at atemperature too low to have optimum operating characteristics. To allowthe engine to pass through this initial heating phase as quickly aspossible, it is advisable to prevent the heat transfer fluid fromflowing in the first heat exchanger so as to be cooled there. This isthe function of the first valve.

It is an object of the invention to optimize the conditions of flow ofthe fluid in the second exchanger.

In particular, the invention has as its object a device of the typedefined at the outset and envisages that the switching means furthermorecomprise a second valve suitable for providing a cross section ofpassage for flow of the fluid in the second exchanger that depends onthe temperature of the fluid: at its maximum below a second thresholdhigher than the first threshold and decreasing progressively between thesecond threshold and a third threshold higher than the latter, and zeroabove the third threshold.

When the temperature of the fluid exceeds the second threshold, it ispossible to reduce its throughput in the second exchanger while at thesame time satisfying any need for heating of the passenger compartment,thus reducing the noise pollution resulting from flow in this exchanger.The third threshold represents a limit which is reached only inexceptional engine load conditions, e.g. when the vehicle is towing acaravan up a long uphill slope, and which it is desirable to exceed aslittle as possible so as to avoid deterioration in the engine or in itsperformance. To do this, the flow of the fluid in the second exchangeris stopped and the entire output of the pump passes through the firstexchanger, which provides a higher cooling capacity than the secondexchanger.

Optional characteristics of the invention, which are complementary oralternatives, are stated below:

-   -   The second valve is a three-way valve, in which said variable        cross section of passage is situated between first and second        channels connected respectively to the engine and the second        exchanger, and is suitable for allowing a flow of fluid between        the third channel, which is connected to a bypass conduit, and        either the first or the second channel only when the temperature        of the fluid is lower than the third threshold.    -   The flow of fluid between the third channel and either the first        or the second channel is allowed only when the temperature of        the fluid is between the second and third thresholds.    -   The first channel is an inlet and the second and third channels        are outlets or vice versa.    -   The flow of fluid between the third channel and either the first        or the second channel is allowed even when the temperature of        the fluid is lower than the second threshold.    -   The first and second channels are inlets and the third channel        is an outlet or vice versa.    -   The three-way valve has a movable member which is displaced        between extreme first and second positions when the temperature        of the fluid varies between the second and third thresholds,        said movable member including a first closing element, which        isolates the first channel from the two other channels, and a        second closing element, which isolates the third channel from        the two other channels, in the second position, the closing        elements opening the corresponding channels when not in the        second position.    -   The movable member includes a third closing element, which        isolates the third channel from the two other channels in the        first position and opens it when not in the first position.    -   The second valve is furthermore suitable for preventing flow of        the fluid in the second exchanger when the two following        conditions are satisfied: temperature of the fluid lower than        the first threshold and no demand for heating of the passenger        compartment.    -   The second valve contains a medium which is in thermal contact        with the heat transfer fluid and the thermal expansion of which        causes the displacement of the movable member, means being        provided to heat said medium independently of the temperature of        the fluid so as to move the movable member into its second        position in response to said two conditions.    -   The means for heating said medium comprise an electrical        resistor in thermal contact with the latter, in series with a        switch, which is closed in response to said conditions.    -   At least one of said thresholds is as defined below:        -   first threshold: about 80° C.        -   second threshold: about 100° C.        -   third threshold: about 110° C.    -   The second valve is of the thermostatic, electric or pneumatic        type.

The characteristics and advantages of the invention will be explained ingreater detail with reference to the drawings in the description whichfollows.

FIG. 1 is a schematic representation of a circuit containing heattransfer fluid in a device according to the invention.

FIGS. 2 a through 2 d are sectional views of a three-way thermostaticvalve belonging to the circuit of FIG. 1 for different temperatures ofthe fluid.

FIG. 3 is a representation similar to FIG. 1 relating to a modifiedcircuit.

FIGS. 4 a to 4 c are views similar to FIGS. 2 a through 2 d, showing avalve that forms part of the circuit in FIG. 3.

Each of the circuits shown in FIGS. 1 and 3 comprises three maincomponents, through which a heat transfer fluid can pass, namely theheat engine 1 for driving a motor vehicle, a radiator 2 provided to coolthe engine 1, and a radiator 3 provided to heat the passengercompartment of the vehicle. In the conventional way, the circuit has,outside the engine, two main branches, in which the fluid can flow,being driven by a pump 4, which is, for example, electric, namely afirst branch 5, which the fluid coming from the engine enters via athermostatic valve 6, passing through the radiator 2 and ending at thepump 4, and a second branch 7, which starts from the engine, passesthrough the radiator 3 and likewise ends at the pump 4. Likewise in aconventional way, an additional branch 8 containing an expansion tank 9starts from the outlet of the valve 6 and rejoins branch 5 at aconnection point A situated downstream of the radiator 2.

In the circuit in FIG. 1, the pump 4 returns to the engine 1 all thefluid flowing in branches 5 and 7. Moreover, a three-way thermostaticvalve 10 is interposed in branch 7, upstream of the radiator 3, andcommunicates via a conduit 11 with a connection point B situated inbranch 7, downstream of the radiator 3. The inlet of the valve 10, whichis connected to the engine 1, its outlet connected to the radiator 3,and its outlet connected to point B are respectively designated by thereferences 10-1, 10-2 and 10-3.

An exemplary embodiment of the valve 10 is shown in FIGS. 2 a through 2d. This valve comprises a valve body formed in two pieces 21 and 22,substantially pieces of revolution about an axis 23, which are assembledwith one another in a fluidtight manner. Piece 21 includes a connectionpiece 24 extending along the axis 23 and defining the inlet 10-1 of thevalve. The outlets 10-2 and 10-3 are defined by connection pieces 25 and26 respectively attached to pieces 21 and 22 and respectively extendingperpendicularly to the axis 23 and obliquely to the latter. Disposedwithin the body 21, 22 is a bulb 30 containing a fluid substance with ahigh coefficient of thermal expansion, and in which a rod 31 can slide,the latter projecting from the bulb by a length that increases thehigher the temperature of the fluid substance and consequently itsvolume. The rod 31 is fixed by its free end to piece 22 and extendsalong the axis 23 in such a way that the bulb 30 moves along this axisas a function of the temperature. An electrical resistor 32 connected toa voltage source via a switch 33 is placed within the bulb 30.

For convenience in the description, it is assumed that the valve 10 isaligned as shown in FIGS. 2 a through 2 d, the axis 23 being vertical,piece 22 being situated in the lower part and connection piece 24 beingturned upward. The bulb 30 can thus move between an extreme lowerposition, shown in FIG. 2 b, in which the rod 31 is retracted to themaximum extent, and an extreme upper position, shown in FIGS. 2 a and 2d, in which the rod 31 is extended to the maximum extent.

The bulb 30 carries three shut-off elements in the form of profiledsheet-metal rings, which are bodies of revolution about the axis 23 andare each suitable for cooperating with a seat formed by a radiallyoriented annular surface of the body to close and open a passage for thefluid within the valve. A first shut-off element 34 cooperates with adownward-facing seat 35 formed in piece 21 below connection piece 24 andabove connection piece 25. A conical spring 36 compressed axiallybetween a shoulder of the bulb 30 and shut-off element 34, presses thelatter against seat 34 in the top position of the bulb in such a way asto isolate inlet 10-1 from the interior of the valve. A shut-off element37 cooperates with a seat 38 of piece 22, which seat faces upward and issituated higher than connection piece 26, in such a way as to isolateoutlet 10-3 from the interior of the valve 10 in the bottom position ofthe bulb. Finally, a shut-off element 39 situated immediately aboveshut-off element 37 cooperates with a seat 40 formed in piece 21, whichseat faces downward and faces seat 38, in such a way as to separate theinterior of the valve, in the high position of the bulb, into an upperchamber communicating with channels 10-1 and 10-2 and a lower chamber 42communicating with channel 10-3. In the example illustrated, shut-offelement 37 is welded to the bulb 30 and shut-off element 39 is welded tothe upper face of shut-off element 37. A helical spring 43, which iscompressed axially between shut-off element 39 and an internal shoulder44 of piece 21, assists the return of the bulb toward its low position.

The circuit in FIG. 1 operates in the following manner. When the engine1 is started cold, the low temperature of the heat transfer fluidcontained in the latter causes the thermostatic valve 6 to close in sucha way that the fluid does not flow in branch 5 and consequently in thecooling radiator 2. Moreover, the switch 33 is jointly controlled as afunction of the temperature of the fluid and of the demand for heatingof the passenger compartment in such a way as to be closed only when thefluid is cold and there is no demand for heating. When the twoconditions are satisfied, as shown in FIG. 2 a, the closure of theswitch 33 leads to the resistor 32 being supplied with power and to thesubstance contained in the bulb 30 being heated, moving the latter intoits upper position, in which shut-off element 34 closes the inlet 10-1connected to the engine. The fluid thus no longer flows in branches 7and 11 and remains within the engine 1, hence ensuring that it heats upas quickly as possible. The pump 4 then idles.

If, on the contrary, heating of the passenger compartment is demanded,the switch 33 is open, as shown in FIG. 2 b, such that the resistor 32is not supplied with power and the bulb is held in a low position by thelow temperature of the fluid. Outlet 10-3 is thus closed by shut-offelement 37, while shut-off element 34 allows communication between inlet10-1 and outlet 10-2. Thus the only throughput of fluid in circulationis that required in the radiator 3 to heat the passenger compartment.

When the temperature of the fluid in the engine reaches a value thatallows the latter to operate in more or less optimum conditions, e.g.80° C., the thermostatic valve 6 opens and the fluid flows in thecooling radiator 2. The same temperature threshold is used, at leastapproximately, to control the switch 33, such that the configuration ofFIG. 2 b, in which a maximum throughput flows in the heating radiator 3,is then obtained both in the case of a demand for heating and in theopposite case, the radiator 3 naturally not being swept by a flow of airin the latter case.

When the temperature of the fluid exceeds a second threshold, e.g. 100°C., the expansion of the substance contained in the bulb 30 due to itbeing immersed in the fluid causes it to rise, as shown in FIG. 2 c.Shut-off element 37 then moves away from seat 38, opening outlet 10-3,such that the fluid entering the valve 10 via the inlet 10-1 isdistributed between the outlet 10-2 leading to the radiator 3 and theoutlet 10-3 returning to the pump 4, the throughput of fluid in theradiator 3 being a decreasing function of its temperature.

Finally, when the temperature of the heat transfer fluid reaches a thirdthreshold, e.g. 110° C., the bulb 30 reaches its high position, as shownin FIG. 2 d, preventing all flow of fluid in branches 7 and 11, asindicated above in relation to FIG. 2 a. As the bulb 30 is raised (FIG.2 c), the cross section of passage between shut-off element 34 and itsseat 35 decreases progressively, such that an increasing fraction of thethroughput created by the pump 4 passes through the radiator 2,improving cooling efficiency. This efficiency is at its greatest in theposition shown in FIG. 2 d, which is only achieved in exceptionalcircumstances, for example when towing a heavy trailer such as a caravanup a long slope.

FIG. 3 shows an engine 1, a cooling radiator 2, a heating radiator 3, abranch 5, a thermostatic valve 6, a branch 8 and an expansion tank 9similar to the elements designated by the same references in FIG. 1.Likewise, one branch 7 of the circuit runs from the outlet of the engine1 to the pump 4, passing via a three-way valve 10 and via the radiator3, the valve 10 being connected to the engine 1 by an inlet 10-1 and tothe radiator 3 by an outlet 10-2. As a departure from FIG. 1, the thirdchannel 10-3 of the valve 10 is an inlet, which is connected to theoutlet of the pump 4 by a branch 12.

The structure of the valve 10 used in the circuit in FIG. 3, which isshown in detail in FIGS. 4 a through 4 c, is the same as that in FIGS. 2a through 2 d, but the valve is connected differently, the channels10-1, 10-2 and 10-3 being defined respectively by the connection pieces26, 25 and 24.

The switch 33 associated with the resistor 32 is controlled as describedabove with reference to FIGS. 2 a and 2 b, such that, when the engine iscold and there is no demand for heating, the configuration in FIG. 4 a,which is identical to that in FIG. 2 a, is obtained, isolating channels10-1 through 10-3 from each other and preventing any flow of fluid inbranches 7 and 12.

In the valve in FIGS. 4 a through 4 c, the minimum length by which therod 31 projects from the bulb 30 is greater than in the valve in FIGS. 2a through 2 d, such that, in the lowest position that can be obtained bythe bulb 30, the switch 33 being open and the engine being cold,shut-off element 37 is out of contact with seat 38 (FIG. 4 b), allowingcommunication between channels 10-1 through 10-3 and flow of the fluidboth in the radiator 3 and in branch 12.

Above the second temperature threshold (100° C.), the rod 31 emergesprogressively from the bulb 30, lifting the latter and moving shut-offelements 34 and 39 closer to seats 35 and 40 respectively, reducing thethroughput of the fluid entering via the inlet 10-1 from the engine andthat entering via the inlet 10-3 from branch 12 and consequently thethroughput of the fluid in the radiator 3, which is the sum of theabove. These two shut-off elements close the corresponding passages(FIG. 4 c) when the temperature of the fluid reaches or exceeds thethird threshold (110° C.), such that all the flow produced by the pump 4passes via the cooling radiator 2.

As indicated above, the valve shown in FIGS. 2 a through 2 d, which isused in the circuit in FIG. 1, and that shown in FIGS. 4 a through 4 c,which is used in the circuit in FIG. 3 are identical with the exceptionof the length of the rod 31. However, it will be noted that shut-offelement 39 is not necessary to the operation of the circuit in FIG. 1since, each time that it is closed (FIGS. 2 a and 2 d), shut-off element34 is likewise closed, preventing any entry of fluid into the valve 10.Shut-off element 39 can therefore be omitted, the spring 44 restingdirectly on shut-off element 37. Likewise, shut-off element 37 is notnecessary to the operation of the circuit in FIG. 3 since it never comesinto contact with seat 38. Shut-off elements 37 and 39 can therefore bereplaced by a single shut-off element fixed on the bulb 30 and cominginto contact with seat 40 in the high position of the bulb.

Moreover, the three-way thermostatic valve can be of a type other thanone employing an expanding substance in thermal contact with the heattransfer fluid. It can be an electrically controlled valve, for example.

Furthermore, the flow of the fluid in branch 7 and in the bypass branch11 or 12 can be reversed relative to that shown in FIGS. 1 and 3, theinlets of the valve 10 becoming outlets and vice versa.

1. A device for cooling the heat engine (1) and heating the passengercompartment of a motor vehicle, comprising a first heat exchanger (2)suitable for contributing to a transfer of heat from a heat transferfluid to the atmosphere, a second heat exchanger (3) suitable forcontributing to a transfer of heat from the heat transfer fluid to thepassenger compartment, a pump (4) suitable for making the fluid flow inthe engine and in two branches (5, 7) in parallel respectivelycontaining the first and second exchangers, and switching means (6, 10),which enable the fluid driven by the pump to flow or not to flow in eachof said exchangers, the switching means comprising a first valve (6)suitable for preventing flow of the fluid in the first exchanger whenits temperature is lower than a first threshold and for allowing it whensaid temperature is higher than the first threshold, characterized inthat the switching means furthermore comprise a second valve (10)suitable for providing a cross section of passage for flow of the fluidin the second exchanger that depends on the temperature of the fluid: atits maximum below a second threshold higher than the first threshold anddecreasing progressively between the second threshold and a thirdthreshold higher than the latter, and zero above the third threshold. 2.The device as claimed in claim 1, in which the second valve is athree-way valve (10), in which said variable cross section of passage issituated between first and second channels (10-1, 10-2) connectedrespectively to the engine and the second exchanger, and is suitable forallowing a flow of fluid between the third channel (10-3), which isconnected to a bypass conduit (11), and either the first or the secondchannel only when the temperature of the fluid is lower than the thirdthreshold.
 3. The device as claimed in claim 2, in which the flow offluid between the third channel and either the first or the secondchannel is allowed only when the temperature of the fluid is between thesecond and third thresholds.
 4. The device as claimed in claim 3, inwhich the first channel (10-1) is an inlet and the second and thirdchannels (10-2, 10-3) are outlets or vice versa.
 5. The device asclaimed in claim 2, in which the flow of fluid between the third channeland either the first or the second channel is allowed even when thetemperature of the fluid is lower than the second threshold.
 6. Thedevice as claimed in claim 5, in which the first and second channels(10-1, 10-2) are inlets and the third channel (10-3) is an outlet orvice versa.
 7. The device as claimed in any of claims 2 through 6, inwhich the three-way valve has a movable member (30) which is displacedbetween extreme first and second positions when the temperature of thefluid varies between the second and third thresholds, said movablemember including a first closing element (34), which isolates the firstchannel (10-1) from the two other channels (10-2, 10-3), and a secondclosing element (39), which isolates the third channel from the twoother channels, in the second position, the closing elements opening thecorresponding channels when not in the second position.
 8. The device asclaimed in claim 7, which is dependent on claim 3, in which the movablemember includes a third closing element (37), which isolates the thirdchannel from the two other channels in the first position and opens itwhen not in the first position.
 9. The device as claimed in any of thepreceding claims, in which the second valve is furthermore suitable forpreventing flow of the fluid in the second exchanger (3) when the twofollowing conditions are satisfied: temperature of the fluid lower thanthe first threshold and no demand for heating of the passengercompartment.
 10. The device as claimed in claim 9, which is dependent onclaim 7, in which the second valve contains a medium which is in thermalcontact with the heat transfer fluid and the thermal expansion of whichcauses the displacement of the movable member, means (32, 33) beingprovided to heat said medium independently of the temperature of thefluid so as to move the movable member (30) into its second position inresponse to said two conditions.
 11. The device as claimed in claim 10,in which the means for heating said medium comprise an electricalresistor (32) in thermal contact with the latter, in series with aswitch (33), which is closed in response to said conditions.
 12. Thedevice as claimed in any of the preceding claims, in which at least oneof said thresholds is as defined below: first threshold: about 80° C.second threshold: about 100° C. third threshold: about 110° C.
 13. Thedevice as claimed in any of the preceding claims, in which the secondvalve (10) is of the thermostatic, electric or pneumatic type.